from sympy import *
from spb import *
x, y, a, b, xp, yp = symbols("x y a b x_p y_p")
expr = (cos(x) + a * sin(x) * sin(y) - b * sin(x) * cos(y))**2
graphics(
    contour(expr, prange(x, 0, xp*pi), prange(y, 0, yp * pi),
        params={
            a: (1, 0, 2), b: (1, 0, 2),
            xp: (1, 0, 2), yp: (2, 0, 2)}),
    grid=False
)